Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D335/00—Heterocyclic compounds containing six-membered rings having one sulfur atom as the only ring hetero atom
  • C07D335/04—Heterocyclic compounds containing six-membered rings having one sulfur atom as the only ring hetero atom condensed with carbocyclic rings or ring systems
  • C07D335/10—Dibenzothiopyrans; Hydrogenated dibenzothiopyrans
  • C07D335/12—Thioxanthenes
  • C07D335/14—Thioxanthenes with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached in position 9
  • C07D335/16—Oxygen atoms, e.g. thioxanthones
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C323/00—Thiols, sulfides, hydropolysulfides or polysulfides substituted by halogen, oxygen or nitrogen atoms, or by sulfur atoms not being part of thio groups
  • C07C323/22—Thiols, sulfides, hydropolysulfides or polysulfides substituted by halogen, oxygen or nitrogen atoms, or by sulfur atoms not being part of thio groups containing thio groups and doubly-bound oxygen atoms bound to the same carbon skeleton
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
  • C07C69/66—Esters of carboxylic acids having esterified carboxylic groups bound to acyclic carbon atoms and having any of the groups OH, O—metal, —CHO, keto, ether, acyloxy, groups, groups, or in the acid moiety
  • C07C69/67—Esters of carboxylic acids having esterified carboxylic groups bound to acyclic carbon atoms and having any of the groups OH, O—metal, —CHO, keto, ether, acyloxy, groups, groups, or in the acid moiety of saturated acids
  • C07C69/708—Ethers
  • C07C69/712—Ethers the hydroxy group of the ester being etherified with a hydroxy compound having the hydroxy group bound to a carbon atom of a six-membered aromatic ring

Definitions

• This invention relates to photoinitiators and particularly, although not exclusively, relates to novel compounds for use as photoinitiators.
• Photoinitiated curing processes may use photoinitiators which generate photo-excited species, which react with the curing agents, commonly called synergists, to produce radicals which are thought to be the species responsible for the polymerisation reaction.
• the curing agents are aromatic tertiary amines.
• Commercial amine curing agents are ethyl-4- (N, N- dimethylamino) benzoate (EDB) and 2-n-butoxyethyl 4- (dimethylamino) benzoate (BEDB) .
• Photoinitiators which are available, and suitable for use with amine curing agents, are thioxanthone initiators, in particular isopropylthioxanthone (ITX) ; anthraquinone initiators; and benzophenone initiators, in particular 2- methylbenzoylbenzoate (2-MBB) .
• IX isopropylthioxanthone
• 2-MBB 2- methylbenzoylbenzoate
• Type 1 Other types of photoinitiators, referred to as Type 1
• I photoinitiators include, for example, benzoin and benzoin derivatives. They may be used alone in a photoinitiated reaction or in combination with an amine compound which may act as an oxygen scavenger.
• Japanese published patent application 6263814 proposes photoinitiators obtained by reacting dihydric polyol compounds with ortho-benzoylbenzoic acid. These are said to be of use in curable coating compositions said to have reduced odour, and to be free from deterioration from curability.
• di(benzoyl benzoate) compound of this type produced by reacting ortho- benzoylbenzoic acid with poly(ethylene glycol) 300 to migrate from a cured polymer at a relatively high rate.
• photoinitiators One major problem associated with known photoinitiators is the relative ease of migration of the photoinitiator from cured polymer since this results in adjacent materials being tainted. When the polymer is, for example, a film and the adjacent materials are, for example, foodstuffs, this is very undesirable.
• This invention is based on the discovery that a photoinitiator can be rendered less susceptible to migration by substitution with groups as described herein.
• a compound for use as a photoinitiator comprising a photoreactive portion and a pendent group, said photoreactive portion including an aromatic moiety and said pendent group incorporating at least one optionally-substituted poly(alkylene glycol) moiety.
• optional substituents described herein include halogen atoms, especially chlorine atoms, and alkyl, acyl, nitro, cyano, alkoxy, hydroxy, amino, alkylamino, sulphinyl, alkylsulphinyl, sulphonyl, alkylsulphonyl, sulphonate, amido, alkylamido, alkoxycarbonyl, halocarbonyl and haloalkyl groups;
• alkyl groups may have up to ten carbon atoms, preferably up to seven carbon atoms, more preferably up to four carbon atoms.
• Preferred alkyl groups include methyl and ethyl groups.
• said optionally substituted poly(alkylene glycol) moiety is of general formula
• R 1 represents an optionally substituted alkyl group
• R 3 and R 5 independently represent a hydrogen atom or an optionally substituted alkyl group and x represents an integer.
• R 1 represents an unsubstituted alkyl group.
• R 1 represents a C,_ 6 alkyl group, more preferably a C M alkyl group. Especially preferred is the case wherein R 1 represents a methyl or ethyl group.
• R 3 and R 5 independently represent a hydrogen atom or an unsubstituted alkyl group.
• R 5 preferably represents a hydrogen atom.
• R 3 represents a hydrogen atom or an alkyl group and R 5 represents a hydrogen atom. More preferably, both R 3 and R 5 represent hydrogen atoms.
• Integer x may have a mean value of greater than 3, suitably greater than 4, preferably greater than 5, more preferably greater than 6. Integer x may have a mean value of less than 20, suitably less than 15, preferably less than 11, more preferably less than .9.
• Said optionally-substituted poly(alkylene glycol) moiety may have an average molecular weight (excluding any optional substituents) of at least 150, suitably 200, preferably 250, more preferably 300, especially 340. Said average molecular weight may be less than 900, suitably 800, preferably 700, more preferably 600, especially 500.
• Said moiety of general formula I may be linked directly to said photoreactive portion via the ether- oxygen atom thereof or may be linked to said photoreactive portion by a linking group arranged between said photoreactive portion and said moiety of formula I.
• a said linking group may include a first moiety of general formula -OCR 2 2 CO- wherein groups R 2 may be the same or different and may represent a hydrogen atom or an optionally substituted, preferably unsubstituted, alkyl group. Preferably, each R 2 represents a hydrogen atom.
• a said linking group may include a group -CO-, instead of said first moiety.
• Said linking group may include an intermediate moiety between said photoreactive portion and said first moiety or group -CO-.
• An intermediate moiety may include a phenyl group and may comprise a group -S-Ph- wherein the sulphur atom is bonded to said photoreactive portion and "Ph" represents an optionally-substituted, especially an unsubstituted, phenyl group.
• said linking group comprises said first moiety wherein the ether oxygen atom of said moiety is bonded to said photoreactive portion.
• the or each pendent group is preferably an aliphatic group.
• said photoreactive portion incorporates an optionally substituted phenylcarbonyl moiety.
• the carbonyl group of said optionally substituted phenyl carbonyl moiety may be bonded to another moiety which may comprise an optionally-substituted phenyl or alkyl moiety. Where it comprises an optionally-substituted phenyl moiety, said moiety may, in turn, be bonded to the phenyl group of said phenylcarbonyl group by an intermediate atom or group which may comprise a group -CO- or -S- thereby to define a ring structure, for example of thioxanthone or anthraquinone.
• Preferred optional substituents on said optionally-substituted phenyl group include optionally- substituted thioalkyl or thiophenyl groups.
• a preferred alkyl group has a general formula -CR 6 R 7 OH where R 6 and R 7 independently represent an optionally-substituted alkyl group or together define a ring, for example a cycloalkyl, especially a cyclohexyl ring.
• Said photoreactive portion may be selected from optionally-substituted benzaldehyde, benzophenone, anthraquinone, thioxanthone, thiophenylbenzophenone (especially 4- (thiophenyl) benzophenone) and benzoin derivatives.
• Preferred benzaldehyde derivatives include 1-hydroxy- cyclohexyl-phenyl ketone, ex, oc-dimethoxy-oc-hydroxy acetophenone , 2 -ben zy 1 - 2 -d imethy1 amino- 1 - ( 4 - morpholinophenyl) -butan-l-one, benzoyl-diphenyl-phosphine oxide and methyl oc-oxobenzeneacetate derivatives.
• Said pendent group may be bonded to said benzaldehyde derivatives in any suitable position. It is preferably bonded to the phenyl group in the case of 1-hydroxy- cyclohexyl-phenyl ketones, oc, oc-dimethoxy-oe-hydroxy acetophenone, methyl ⁇ -oxobenzeneacetate and 2-benzyl-2- dimethylamino-1- (4-morpholinophenyl) -butan-l-one derivatives. It is preferably bonded to the benzoyl group in the case of benzoy1-dipheny1-phosphine oxide derivatives.
• said photoreactive portion is a benzophenone derivative
• said derivative is preferably substituted by one or two pendent groups as described above, said groups suitably being substituted at the 4- and/or 4'- positions.
• said photoreactive portion is an anthraquinone or thioxanthone derivative
• said derivative is preferably substituted by one or two pendent groups as described above, said groups suitably being substituted at the 1- and/or 8- positions.
• a thioxanthone derivative may be substituted by a pendent group at the 1- position and a halogen, especially a chlorine atom, at another position, especially the 4- position.
• said photoreactive portion is a thiophenylbenzophenone derivative
• said thiophenyl group of said derivative may be substituted by a said pendent group as described above, preferably at the 4- position.
• benzoin derivatives include benzoin per se. benzoin ethers, for example benzoin ethyl ether, isopropyl ether, n-butyl ether and i-butyl ether, and benzilketals.
• benzoin derivatives may be substituted by one or two pendent groups as described above.
• said benzoin derivatives may be substituted on the benzene rings, or the hydroxy group of benzoin may be substituted with a said pendent group.
• a benzilketal may be substituted on the benzene rings or on the ketal carbon atom.
• said photoreactive portion is selected from optionally substituted, more preferably mono- substituted or unsubstituted, benzophenone, anthraquinone and thioxanthone; or from a group of general formula Z-CO- Ph wherein Z represents an optionally-substituted alkyl group and Ph represent an optionally-substituted phenyl group.
• step (ii) reacting the product of step (b) (i) with a moiety corresponding to a second portion of said photoreactive portion; and iii) optionally derivatising said precursor of said pendent group.
• said active atoms or groups are selected from halogen atoms or hydroxy or alkoxy groups.
• said photoreactive portion preferably includes one or more hydroxy groups at each position wherein it is desired to provide a said pendent group.
• Each said precursor of said pendent group which is to be reacted preferably includes a halogen atom, especially a bromine atom, which activates said precursor and enables the oxygen atom of a said hydroxy group to attack the carbon atom bearing the halogen atom in a nucleophilic substitution reaction.
• the reaction is suitably carried out in an aprotic solvent, in the presence of a base, suitably an inorganic base, under reflux.
• the precursor used in step a(i) may correspond to said pendent group in said compound of the first aspect in which case step a(ii) may not be required.
• the precursor used in step a(i) may need further derivisation to provide said pendent group of said compound of the first aspect.
• the compound used in step (a) (i) may comprise a precursor with two active atoms or groups, for example a halogen, especially a bromine atom as described above and an ester group. Then in step (a) (ii) , said ester group may be transesterified to provide the desired pendent group.
• a photoreactive portion including one or more hydroxy groups is reacted with a precursor which includes a bromine atom and an ester group.
• the bromine atom activates the precursor which reacts with a said hydroxy group to form an ether linkage.
• the ester group can then be transesterified with an optionally substituted poly(alkylene glycol) moiety to produce the desired compound.
• the transesterification process may be carried out under standard conditions.
• a salt of a hydroxy derivative corresponding to said photoreactive portion is reacted with a halogenated, especially a chlorinated, compound corresponding to the desired pendent group.
• Process (a) is the preferred process for preparation of most of the compounds of the first aspect.
• Process (b) may be used for the preparation of compounds which include complex photoreactive portions.
• said first portion may be activated by means of an alkoxide group and may be reacted with a precursor group activated, for example, by a tosylate group.
• a second active group on said first portion may be derivatised and/or further reacted with a suitably activated second portion of said photoreactive portion.
• process (b) may be used for the preparation of thiophenylbehzophenone derivatives by reacting potassium 4-nitrophenoxide with methoxy poly(ethylene glycol) tosylate, followed by reduction of the nitro group to an amine which can then be diazotised and reacted with sodium sulphide to produce a thiophenyl derivate.
• the thiophenyl derivative can then be reacted with suitably activated, for example by a chlorine atom, benzophenone to produce the desired compound.
• suitably activated for example by a chlorine atom, benzophenone
• Other compounds which fall within the scope of the present invention are commercially available and/or may be prepared by derivatising commercially available compounds using processes analogous to those described herein.
• the invention extends to the use of a compound according to said first aspect in a polymerisation reaction.
• a polymer curing composition which may be in kit form, comprising a compound according to said first aspect, together with a curing agent with which the compound of general formula I may react, when irradiated, to generate a polymerisation specie, for example a radical.
• a polymerisable composition comprising a polymerisable material suitably present in an amount from 80 to 99 wt% and a compound of the first aspect, suitably present in an amount from 20 to 1 wt. %.
• the composition may further include a curing agent, suitably present in an amount from 14 to 2 wt%.
• a curing agent suitably present in an amount from 14 to 2 wt%.
• said polymerisation material is present in an amount from 80 to 97 wt% and said compound of the first aspect is present in an amount from 6 to 1 wt%. 5 wt% or less, preferably 4 wt% or less, more preferably 3 wt% or less of said compound of said first aspect may be present.
• a polymeric composition prepared using a compound according to said first aspect or said polymerisable composition by photo-curing.
• a suitable curing agent may, for example, be an aromatic amine compound, for example ethyl-4-(N,N- dimethylamino) benzoate (EDB) or 2-n-butoxyethyl 4- (dimethylamino) benzoate (BEDB) or a curing agent described in our PCT patent application number PCT/GB96/00910 or a co-filed application entitled Amine Compounds. The contents of both applications are incorporated herein by reference.
• EDB ethyl-4-(N,N- dimethylamino) benzoate
• BEDB 2-n-butoxyethyl 4- (dimethylamino) benzoate
• a suitable polymerisable material is any material whose polymerisation can be initiated by a radical, especially an amine radical.
• the polymerisation is applied to acrylate systems where the polymerisable material (monomer) may, for example be 1,6- hexanediol diacrylate (HDDA) , 2-hydroxyethyl acrylate (HEA) , hydroxypropy1 acrylate (HPA) and methyl methacrylate (MMA) .
• HDDA 1,6- hexanediol diacrylate
• HPA 2-hydroxyethyl acrylate
• HPA hydroxypropy1 acrylate
• MMA methyl methacrylate
• the polymerisable materials may be suitable for surface/coating/film applications. They may be formulated with other components, including inks, for printing applications.
• Figure 1 is a graph of % migration versus number of passes of a Colordry lamp for compounds 1, 2 and Cl described hereinafter;
• Figure 2 is a graph of absorbence versus number of passes for compounds 3, C2 and C3 described hereinafter;
• Figure 3 is a graph of % migration versus number of passes of a Colordry lamp for the compounds shown in figure 2.
• Figures 4, 6, 8, 10 and 13 are graphs of absorbence versus number of passes for respective sets of examples (3, 4, 5, C3, C6) , (8, 9) , (C7, C8, 11), (6) and (CIO, 12, 13, 14) ;
• Figures 5, 7, 9, 12 and 14 are graphs of % migration versus number of passes for respective sets of examples (3, 4, 5, C3, C6) , (8, 9), (C7, C8, 11), (C9, 7) and (CIO, 12, 13, 14).
• Figure 11 is a graph of % extent of reaction versus time (sees) for compounds 7 and C9, as assessed using RTIR.
• Step 1 The product of Step 1 was transesterified in toluence under reflux with poly(ethylene glycol) 350 monomethylether in a dry environment using a Tilcom BIP catalyst (butyl isopropyl titanate)to give a viscous orange product.
• Tilcom BIP catalyst butyl isopropyl titanate
• the product was left under high vacuum for 24 hours in an attempt to remove all traces of toluene and characterised by HPLC and proton NMR in CDC1 3 , the results being as follows:
• HPLC Two sets of peaks corresponding to mono- and di- substituted PEG compounds after 5 hours reflux. The peaks convert to one set of peaks (under the same conditions) after a further 5 hours reflux.
• Step 1 of the process described above for the preparation of compound 1 was repeated except that 4,4'- dihydr oxybenzophenone was replaced with 1,8- dihydroxyanthraquinone .
• the resulting compound was characterised as follows:
• Step 2 Step 2 of the process described above for compound 1 was repeated, using the product of latter mentioned Step 1.
• the resulting compound was characterised as follows:
• Step 1 of the process described above for the preparation of compound 1 was repeated except that 4,4'- dihydroxybenzophenone was replaced with a mixture of 2- and 4-hydroxy thioxanthone.
• the resulting compound was characterised as follows:
• Step 2 of the process described above for compound 1 was repeated, using the product of the latter mentioned Step 1.
• the resulting compound was characterised as follows: NMR:
• Example 3 These were as described in Example 3, except that 4- hydroxythioxanthone was used as a starting material instead of 4,4 1 -dihydroxybenzophenone.
• Step 1 The product of Step 1 was treated as described in Example 1, Steps 1 and 2 to prepare the desired compound which was characterised as follows:
• Compound 6 a mixture consisting essentially of (monomethylpolyethylene glycol) 3;o ether of 2- and 4- thioxanthone
• the chloro derivative of monomethylpolyethylene glycol-350 was prepared by reacting thionyl chloride with commercially available monomethyl PEG-350 as described in US 4 602 097 except that dimethylformamide referred to was replaced with a slight molar excess of pyridine and, in the process, the thionyl chloride solution was added with cooling, and subsequent heating at 40°C for 10 hours was used instead of refluxing. Overnight, the pyridine hydochloride salt separated and the desired chloro derivative was decanted. Infra-red analysis showed the absence of an O-H stretch in the product.
• Step 2 The sodium salt of hydroxythioxanthone was prepared by addition of the corresponding hydroxythioxanthone to methanol followed by addition of solid sodium methoxide. Confirmation of salt formulation was by a change of colour from yellow to blood red. The product was evaporated to dryness to yield a brick-red solid that was used without further purification.
• the title compound was prepared by reacting the products of Step l and 2 together in dimethylformamide. Sodium chloride precipitated the mixture was filtered and the desired product isolated by standard techniques.
• Step 3 Preparation of 4 -thi ophenyl -4 ' - hydroxybenzophenone.
• Step 2 The product of Step 2 (l.25g) was added to hydrogen bromide (40%aq solution; 20ml) and glacial acetic acid (20ml) and refluxed for 30 minutes. Acetic anhydride (20ml) was added with cooling, followed by refluxing for 3 hours. Acetic acid was removed under vacuum and the residue was added to water (50ml) which was extracted with dichloromethane. The organic phase was extracted with sodium hydroxide solution (0.5M) and acidified to yield an ivory precipitate which was filtered and reerystallized from methanol/water (2:1). Characterising data is provided in Table 2.
• Step 4 ⁇ Preparation of ethylester of (4-thiophenyl-4'- carboxymethoxy) benzophenone
• the product of Step 3(3g) , potassium carbonate (3g) , ethylbromoaeetate (2.22ml) and acetone (50ml) were refluxed for 36 hours.
• the salt was filtered and the solvent and excess ethylbromoaeetate removed under vacuum to yield a white solid which was reerystallized from ethanol. Characterizing data is provided in Table 2.
• Step 5 Preparation of fmonomethylpolvethyleneqlvcol) 35 r. ester of f4-thiophenyl-4-carboxymethoxy)benzophenone
• Step 1 The product of Step 1 (8g) was added to hydrogen bromide (40% aq solution; 70ml) and glacial acetic acid
• Step 3 Preparation of ethylester of (4-methylthio-4'- carboxymethoxy)benzophenone
• the product of Step 2 (3g) , potassium carbonate (3g) and ethylbromoaeetate (2.8ml) were added to acetone (50ml) .
• the reaction conditions were as described above in Step 4 for Compound 1.
• the product was reerystallized from ethanol. Characterizing data is provided in Table 3.
• Step 4 Preparation of (monomethylpolyethyleneqlvcol) 3!i0 ester of (4-methylthio-4'-carboxymethoxy)benzophenone
• Step 3 The product of Step 3 (2.5g) and polyethyleneglycol monomethyl ester (M ⁇ SO; 2.65g) were added to xylene (50ml) .
• the reaction conditions were as described above in Step 5 for Compound 1.
• the final product was purified by column chromatography. Characterizing data is provided below.
• UV-Vis 0.001% w/v in methanol, 204.0 nm; 1.1856 abs units; 312.0 nm; 0.6835 abs units
• Step 1 Preparation of 4-Methoxy phenyl isopopyl ketone
• Step 2 Preparation of 4-Hydroxy phenyl isopropyl ketone
• the product of Step 1 (lOg; 0.056 moles) was added to a stirred solution of HBr (40ml, 40% aq.solution) and glacial acetic acid (40ml) .
• the solution was refluxed for 30 minutes than acetic anhydride (30ml) was added with cooling and the solution refluxed for 2 hours.
• the volume was reduced and diluted with water (200ml) followed by extraction with dichloromethane.
• the organic fraction was washed with copious amounts of water and then extracted with NaOH(aq) solution (IM) .
• the basic solution was acidified with cone. HCl and the resulting mixture extracted with dichloromethane.
• Step 3 Preparation of acetate ester of l-(4-hvdroxy phenyl) 2-hvdroxy-2-methyl-propan-l-one
• the product of Step 2 (3.5g; 0.021 moles) was added to acetic anhydride (125 ml) and refluxed for 10 hours. Acetic anhydride was removed under vacuum and the residue added to dichloromethane. The organic solution was washed with water and sodium bicarbonate solution before drying over sodium sulphate. The crude product was purified by distillation to yield the target compound as a colourless liquid (3.6g, 83%).
• Step 4 Preparation of acetate ester of l-(4-hydroxy phenyl) -2-bromo-2-methyl-propan-l-one
• the product of Step 3 (25g; 0.12 moles) was added to glacial acetic acid (35ml).
• a solution of bromine (7.8ml; 0.15 moles) in glacial acetic acid (20ml) solution was dropped onto the solution which was stirred at room temperature for 12 hours.
• the reaction solution was added to ice (200g) and the resulting mixture extracted with ethyl acetate.
• the organic fraction was washed with water and dried over sodium sulphate. Removal of solvent yielded the target compound as a straw coloured liquid, that was used without further purification.
• Step 5 Preparation of l-r4-hvdroxypheny!12-hvdroxy- 2-methyl-propan-l-one
• ethanol 120ml
• IM NaOH
• aq aq
• IM aqueous solution
• the aqueous solution was acidified to ⁇ pH 5 with 5M HC1 (J1 ⁇ 1) and extracted with ethyl acetate.
• the organic fraction was dried over sodium sulphate. Removal of solvent yielded the target compound as a white solid (10. lg, 46.7%) .
• Step 6 Preparation of title compound
• the product of Step 5 (3g; 0.0167 moles), potassium carbonate (5g) and either 7.25g of the tosylate ester of polyethylene glycol 3J0 monomethylether or 6g of the chloro- derivative of polyethylene glycol 350 monomethylether, were refluxed in acetone (50ml) for 18 hours.
• the inorganic salts were filtered and the crude product was purified by column chromatography(200-400 mesh silica gel,2:l ethyl acetate/pet ether bp. 40-60°C) to yield the target compound as a viscous liquid.
• Compound C2 A mixture comprising ethyl-2- ( c a r b oxymeth o xy ) t h i o xa n th o n e and ethyl-4- (carboxymethoxy)thioxanthone.
• Curing was by a medium pressure UV lamp.
• the results presented below relate to the determination of whether the polymer cures and if so, how quickly, and to the propensity of the photoinitiators to migrate from a polymer film after curing.
• the two methods employed to address these aspects were Reflectance FTIR analysis and High Pressure Liquid Chromography (HPLC) .
• the extent of reaction was determined by transmittance FTIR as shown in figure 11.
• the degree of cure in films, exposed to UV light was determined as follows:
• the method for testing the propensity of the initiators to migrate was the same throughout.
• the migratable initiator content of each film was analysed as follows. Initially a drop of the pre-polymer mixture was placed on a piece of satinised paper. This was then evenly spread over the surface using a "K" bar which gave a film thickness of between 50-60 ⁇ m.
• the Colordry unit contains a fusion lamp system (a hydrogen bulb electrode-less lamp) .
• the samples are placed on a moving belt (in these trials this was set at 45 metres/minute) . It was important to ensure that all the samples taken, of satinised paper and film, were of the same size. It was for this reason that a metal template was made that gave samples of 25 x 60 mm.
• steps were taken to ensure that the curing of the film was as unaffected by oxygen inhibition as possible. This was ensured by placing the paper and uncured film in a cell with a quartz window. This cell was then evacuated with nitrogen and sealed. Only then was the sample passed through the Colordry unit.
• the only examples wherein polymerisation was carried out in air were those shown in figures 8, 9, 13 and 4.
• each pre-polymer mixture was then placed in individual 7 ml sample vials.
• To each vial was added 5 ml of a de-gassed acetonitrile/water 50/50 mix, enough to immerse each sample.
• the vials were then placed in a dark cupboard for 20 hours. After this time the vials were removed and the sample extracted from each vial. All that was left in each vial was the solvent containing the migratables that had leached out from the film in the 20 hour period.
• the samples were then prepared for HPLC analysis by filtering each one using Sartorus Millistart 0.45 ⁇ m disposable filters. This was to ensure that there were no solid contaminants that would damage the HPLC column.
• each sample was injected on to the HPLC column. Each sample was run in acetonitrile/water 50/50 mixture. The data from each run was then used to analyse the migratable content of each film.
• Table 1 reproduces part of Table 1 in the applicant's co-pending application number PCT/GB96/00911 in order to compare % migration of compounds C4 and C5 (compounds 2 and Cl in PCT/GB96/00911) .
• the compounds referred to in the table were components of a composition comprising: 1,6- hexanediol diacrylate(monomer) (93wt%) ; amine curing agent, N-methyldiethanolamine (5wt%) ; and photoinitiator (2wt%) .
• compounds 1 to 3 are as effective initiators as compounds C3 and C4 (weight for weight) . This is surprising since compounds containing a PEG moiety have significantly greater molecular weights compared to, for example, compounds Cl, C2, C3 and, therefore, the molar ratio of compounds 1 to 3 used is significantly less than that for Cl, C2 and C3.

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• 1996
  • 1996-06-21 GB GBGB9613114.9A patent/GB9613114D0/en active Pending
• 1997
  • 1997-06-23 CA CA002252784A patent/CA2252784A1/en not_active Abandoned
  • 1997-06-23 WO PCT/GB1997/001690 patent/WO1997049664A1/en not_active Application Discontinuation
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